1. Field of the Invention
The present invention relates to an apparatus for a mobile terminal, and more particularly, to a mobile terminal and method of eliminating a call sound noise thereof. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for eliminating a white noise generated during a call of the mobile terminal.
2. Discussion of the Related Art
Generally, while a call is connected between mobile terminals, an interval, for which an originator does not talk to a recipient, is called a speechless interval.
In particular, a recipient terminal does not receive a voice of a user of an originator terminal during the speechless interval but receives a signal containing peripheral noise of the originator terminal, i.e., a white noise.
As a voice encoder of a mobile terminal, an enhanced variable rate speed codec (hereinafter abbreviated EVRC) vocoder is widely used.
The EVRC is used for the synchronous CDMA mobile phone service and is a system for encoding voice information variably according to an information amount of voice.
In particular, since the voice information amount is considerably large in a speech interval for which a caller speaks much, encoding is carried out at a high rate.
In the speechless interval for which a caller does not speak, the voice information amount is almost zero, encoding is carried out at a low rate.
Thus, the vocoder of the originator terminal transmits a white noise during a speechless interval to the recipient terminal in a manner of compressing the white noise into data having an information amount ⅛ smaller than that of a normal speech interval.
However, if the data compressed at the ⅛ rate is decoded by the recipient terminal, it is decoded into a white noise to generate a noise while a call is processed.
So, an automatic audio gain control (AGC) is used to eliminate the white noise, which brings about other problems such as voice fluctuations in a call, voice disconnections in a call, and the like.